1. Field of the Invention
This application generally relates to cellular networks, and more particularly to techniques for planning and tuning a cellular network.
2. Description of Related Art
Cellular networks may be used in a variety of applications. For example, cellular networks are used in cellular telephone communications. Cellular networks include, for example, digital and analog cellular networks that operate in accordance with one or more protocols or standards, such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), IS-95, or Advanced Mobile Phone Service (AMPS). Generally, cellular networks are configured prior to operation in accordance with certain quality standards, conditions and constraints. Examples of the foregoing include, minimizing interference to base stations or sectors. Additionally, the FCC defines frequency ranges that may be assigned and used for transmissions in cellular networks. A base station may be defined as including one or more sectors. Each sector may be viewed as a point from which, or through which, transmissions within the cellular network may be made.
One problem with cellular networks is how to configure the cellular network having multiple sectors, and assigning or associating channels or frequencies with each of these sectors. In other words, part of the configuration of the cellular network is defining at what frequencies different sectors may operate. Sectors may be assigned channels related to information transmissions, such as cellular telephone calls, as well as particular ones for communications related to transmission set up. This association of one of more of one or more channels or frequencies with each of the sectors is determined prior to operation of the cellular network. Additionally, only certain ranges may be used as defined, for example, in accordance with FCC regulations. The FCC defines bands of frequencies that include a limited number of channels which are divided among the various sectors within the cellular network for transmissions.
In a heavily loaded cellular system, the limited number of frequencies or channels may be a problem. One solution is to reuse certain frequencies and assign the same frequency or channel to more than one sector. However, reusing channels when configuring the cellular network may cause the task of system configuration to become increasingly complex due to the constraints that are considered in system configuration. For example, two sectors which are adjacent may generally not be assigned the same frequency due to the extensive interference and operational problems that may be introduced.
Consequently, part of the process of configuring a cellular network may include determining what frequencies may be reassigned to which sectors while trying to minimize the interference which may be introduced by having multiple sectors or base-stations operating at the same frequency. Determining which frequencies may be reassigned or associated with multiple sectors is considered in accordance with quality of service standards, for example, such that a signal is transmitted at a certain power with minimal interference.
Thus, there is required a technique for configuring a cellular network in accordance with input configurations constraints as well as quality of service constraints to achieve a high degree of quality signals by minimizing the interference in a specific set of output configuration data.
In accordance with principles of the invention, disclosed is a method executed in a computer system for determining selection criteria in performing channel assignments in a cellular network. A first time estimate is determined for a single channel assignment in accordance with a first set of selection criteria. A total time estimate is determined using said first time estimate. A determination is made as to whether the total time estimate is acceptable in accordance with a predetermined time threshold.
In accordance with yet another aspect of the invention is a method and computer program product for determining a channel assignment. A set of assignment criteria is selected in accordance with a predetermined level of complexity. For each pair of sectors, it is determined whether each pair are probable neighbors. Pairwise carrier to inteference values are determined for each pair of sectors if the pairwise carrier to interference values are included in the selected set of assignment criteria. A channel assignment is determined using the probable neighbors and the pairwise carrier to interference values in determining whether to perform a channel assignment.
In accordance with yet another aspect of the invention is a method and computer program product for determining carrier to interference values. A set of assignment criteria is selected in accordance with a predetermined level of complexity. Pairwise carrier to interference values are determined for each pair of sectors in accordance with the set of assignment criteria. Total carrier to interference values are determined by combining the one or more pairwise carrier to interference values.
In accordance with yet another aspect of the invention is a method and computer program product for determining a channel assignment for use in a cellular network. One or more assignment criteria is selected from a plurality of assignment criteria options. The channel assignment is determined, in accordance with the one or more assignment criteria, using carrier to interference values and a predetermined threshold representing a quality of service criteria.